1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a plasma display panel, in which a differential dielectric is formed on an upper plate to reduce breakdown voltage and discharge current, and a method for manufacturing the same.
2. Discussion of the Related Art
Generally, in a plasma display panel, discharge cells are divided from each other by barrier ribs formed between a front substrate and a rear substrate. Each of the discharge cells is filled with a main discharge gas, such as neon gas, helium gas, or neon-helium mixed gas, and an inactive gas containing a small amount of xenon. When an electric discharge occurs by means of a high-frequency voltage, the inactive gas generates vacuum ultraviolet rays, and the vacuum ultraviolet rays cause fluorescent materials between the barrier ribs to emit light, thereby forming an image. The above-described plasma display panel has a small thickness and a light weight, thus being spotlighted as the next generation display device.
FIG. 1 is a schematic perspective view of a conventional plasma display panel. As shown in FIG. 1, a plurality of pairs of retaining electrodes, each of which includes a scan electrode 102 and a sustain electrode 103, are arranged on a front glass 101, serving as a display plane, on which an image is displayed, of a front substrate 100 of the plasma display panel. A plurality of address electrodes 113 are arranged on a rear glass 111 of a rear substrate 110 in such a manner that the address electrodes 113 intersect the pairs of the retaining electrodes. The rear substrate 110 is connected to the front substrate 100 in parallel under the condition that the rear substrate 110 and the front substrate 100 are spaced from each other by a designated distance.
Barrier ribs 112 formed in a stripe type (or a well type) for forming a plurality of discharge spaces, i.e., discharge cells, are arranged in parallel on the rear substrate 110. Further, a plurality of the address electrodes 113 for performing address discharge to generate vacuum ultraviolet rays are arranged in parallel with the barrier ribs 112. R, G, B fluorescent materials 114 for emitting visible rays to display an image when the address discharge occurs are applied to the upper surface of the rear substrate 110. A lower dielectric layer 115 for protecting the address electrodes 113 is formed between the address electrodes 113 and R, G, B fluorescent materials 114.
The above conventional plasma display panel is manufactured through a glass-manufacturing process, a front substrate-manufacturing process, a rear substrate-manufacturing process, and an assembling process.
First, the front substrate-manufacturing process includes forming scan electrodes and sustain electrodes on a front glass, forming an upper dielectric layer for limiting discharge current of the scan and sustain electrodes and insulating pairs of the scan and sustain electrodes from each other, and forming a protection layer on the upper dielectric by depositing magnesium oxide for facilitating the discharge condition
The rear substrate-manufacturing process includes forming address electrodes on a rear glass, forming a lower dielectric layer for protecting the address electrodes, forming barrier ribs on the upper surface of the lower dielectric layer for dividing discharge cells from each other, and forming a fluorescent material layer on regions between the barrier ribs for emitting visible rays.
The above plasma display panel and the method for manufacturing the same have problems, as follows.
In order to improve the light-emitting efficiency of the plasma display panel, it is necessary to reduce discharge current. The discharge current is influenced by the thickness of the dielectric layer. Generally, when the dielectric layer has a small thickness, breakdown voltage is decreased and discharge current is increased, and when the dielectric layer has a large thickness, the breakdown voltage is increased and the discharge current is decreased. Accordingly, when the thickness of the dielectric layer is simply increased, the discharge current is decreased, but the breakdown voltage is increased.
In order to solve the above problem, the formation of a differential dielectric layer having different thicknesses according to regions on the upper plate has been proposed. That is, grooves or protrusions are formed on the dielectric layer, thus improving the discharge efficiency of the plasma display panel and reducing power consumption.
The formation of the differential dielectric layer is achieved by a screen printing method or a sanding method.
The screen printing method has a simple process and requires low-priced equipment, but deteriorates the uniformity of the thickness and the width of a layer to be formed, thus lowering the accuracy of a fine definition pattern. Further, the screen printing method leaves mesh marks of a screen mask even after a baking process, thus lowering a surface roughness. Particularly, in a large-sized panel, the screen printing method deforms the screen mask, thus causing disagreement of patterns.
The sanding method is a method in that a dielectric layer is selectively cut using kinetic energy of cutting particles, such as ceramic particles or ultrafine particles of calcium carbonate through a mask patterned on the dielectric layer, thus forming a differential dielectric. The sanding method is capable of produce the differential dielectric having a line width of less than 50 μm. However, the sanding method causes environmental contamination due to dust, and cracks in a fine-definition pattern due to the crushing energy of the cutting particles.